Twist Top Hole Saw

ABSTRACT

A separating Hole Saw with an off-center locking system is disclosed. The ability to rotate and release the top section, with its attached tapered pilot bit, from the circular saw blade allows for the ease of extraction of that pilot bit from the sawed material, while at the same time provides access to the top of that sawed material. This access offers easy removal of the material that remains within the cavity of the circular saw blade.

BACKGROUND OF TILE INVENTION

Hole saws generally retain, within the cavity of the circular saw blade,that portion (core) of the material that the saw has penetrated. Thiscore is usually difficult to remove due to the limited tolerancesbetween the core and the saw blade, and between the core and the pilotbit; the latter extending through the center of the core and slightlypast the toothed end of the saw. This invention will provide a methodfor easy removal of that core.

SUMMARY OF TILE INVENTION

The Hole Saw referenced here is of the basic design. That is, a circularSaw Blade with teeth cut into the lower portion and a Pilot Bit and BitShank attached to a planner surface on the other. However, thisinvention significantly improves on this basic design in that itincorporates a unique locking feature on the planner surface. Thisfeature temporarily, but firmly, attaches the aforementioned plannersurface to the Saw Blade; yet allows for the quick and easy removal ofthat surface after the saw has penetrated an object. Many times thispenetrating action leaves the core of the penetrated object within theconfines of the saw blade. By rotating (unlocking) the planner surfaceit can be lifted from the upper portion of the Saw Blade; extracting thePilot Bit from and exposing the top surface of the core. The core willthen either fall from the confines of the saw or can be pushed from thesaw with the light pressure of the thumb or the tap of a hammer.

Description of the drawings enclosed herewith is as follows:

FIG. 1 is a plan view of the Hole Saw with the top Fan 7 removed, and

FIG. 2 is its sectional view in elevation.

FIG. 3 is a plan view of the Mandrel.

FIG. 4 is its view in elevation and

FIG. 5 its sectional view in elevation.

FIG. 6 is a plan view of the Fan 7, and

FIG. 7 is its sectional view in elevation.

FIG. 8 is a sequence of alternating plan and elevation views of one setof the fan locking device, resulting in a plan view of the lockingdevice as it appears attached to one side of the top of the Hole Saw.

FIG. 9 is a sectional view of the Hole Saw showing its Base Ring 9, BaseRing Skirt 10 and locking device, Fan Stop 6 and Fan Guide 5.

FIG. 10 is a plan view of the Hole Saw, and

FIG. 11 is its view in elevation.

FIGS. 10 & 12 is a plan view showing the Fan 7 in the unlocked position.

FIG. 13 shows the Fan 7 in the locked position with a portion of the FanGuide 5 depicted so as to show the locking feature provided by theLocking Indent 5 b and the Locking Washer 14.

FIG. 14 shows a fragmentary plan view of all elements of the Hole Saw.

FIG. 15 is a sectional view in elevation of the Hole Saw, showing allelements with the exception of the Set Screw 4

DETAILED DESCRIPTION OF THE INVENTION

The version of the invention discussed here includes:

-   -   1. A drill bit shank—Bit Shank.    -   2. A six sided steel shaft center drilled for a drill bit        shank—Hex Shank.    -   3. A steel cylinder center drilled and threaded, then tapped for        a setscrew on the side. The lower portion reduced in diameter        and threaded, then a cavity drilled into its center—Collar.    -   4. Set Screw.    -   5. A bowed steel strip displaying an arc of approximately        eighty-three degrees—Fan Guide.        -   Beveled edge to 5 above—5 a.        -   Arced indent at beveled end of 5 above—Locking Indent 5 b    -   6. A bowed steel strip displaying an arc of approximately        eighty-seven degrees—Fan Stop.        -   Beveled edge to 6 above—6 a.    -   7. A rounded steel plate with diametrically opposed curved        sides. Each side increasing approximately twenty three percent        in radius along one hundred eighty degrees of its        circumference—Fan.    -   8. Circular steel disk—Fan Centering Disk.    -   9. Steel ring with a large center opening—Base Ring.    -   10. Skirt attached to the Base Ring—Base Ring Skirt.    -   11. Tapered Pilot Bit—Pilot Bit.    -   12. Circular steel saw blade—Saw Blade.    -   13. Spacing between Fan Guide and Fan Stop—Clearance.    -   14. Rubber washer—Locking Washer.    -   15. Round head bolt—Washer Bolt.

The invention consists of three primary units: Mandrel, Fan and Saw:

Mandrel Unit, FIGS. 3, 4 & 5: The lower portion of a steel cylinder isreduced in diameter and threaded. A large hole is drilled lengthwiseinto the center of the threaded section creating a cavity, Acenter-threaded hole is drilled into the top portion of the cylinder. Asmaller hole, that will accept a Bit Shank 1, is continued through thecylinder. To secure this Bit Shank 1, a threaded hole is drilled intothe side of the upper section of the cylinder and a Set Screw 4 isplaced therein. This completes the manufacturing of the Collar 3. A holeis drilled lengthwise through the center of a Hex Shank 2. The lowerportion of the Hex Shank 2 is threaded to fit into the top of the Collar3. The Hex Shank 2 is screwed into the top of the Collar 3. The BitShank 1 of the Pilot Bit 11 is inserted through the center of the Collar3 and Hex Shank 2 and is secured with a Setscrew 4.

Saw Unit, FIG. 1&2: A steel disk is made into a ring with a largeopening. A portion of the outer circumference of the ring is turned downninety degrees to form a skirt, thereby creating the Base Ring 9 withits Base Ring Skirt 10. A Saw Blade 12 is wrapped around and attached tothe Base Ring Skirt 10. A portion of the Saw Blade 12 will extend upwardpast the Base Ring 9, a length necessary to contact the outercircumference of the Fan Stops 6 and Fan Guides 5.

The Fan Stops 6, consisting of two bowed steel strips, slightlyincreasing in width along their lengths and beveled at the wide end 6 a,are attached to the top of the Base Ring 9. The Fan Guides 5, consistingof two bowed steel strips slightly increasing in width along theirlengths and beveled at the wide end 5 a, are attached to the top of andslightly overlap the Fan Stops 6. The outer circumferences of thesestrips lay along and are attached to the interior circumference of theupper portion of the Saw Blade 12. A slight arced indentation, lockingIndent 5 b, is cut into the inner edge of the Fan Guide 5 near thebeveled edge 5 a. The stacking sequence of the strips is displayed inboth elevation and plan view in FIG. 8; with FIG. 9 showing a sectionalview in elevation of the assembled parts. Parts 5, 6, 9 and 10 may beconstructed from a solid piece of steel.

Fan Unit, FIGS. 6 & 7: A steel plate described as Fan 7 is constructedsuch that it appears as two opposing half disks, each offset from centerapproximately ten percent of their respective radii. To the bottom ofthis plate is centered and attached a circular steel disk described asFan Centering Disk 8. Next a hole is drilled and threaded through thecenter of these two pieces. The Fan 7 and Fan Centering Disk 8 may bemade from a solid piece of steel. Two holes, diametrically opposed, aredrilled and tapped near the edge of the Fan 7, and a Locking Washer 14is placed over each hole and secured to the surface of the Fan 7 with aWasher Bolt 15. The placement of the Locking Washer 14 is such that itwill press into the Locking Indent 5 b on the Fan Guide 5 when the Fan 7is rotated to the locked position as shown in FIG. 13.

All portions of the Hole Saw are now manufactured and assembled asfollows:

The Collar 3 of the Mandrel, FIGS. 3, 4 & 5, is screwed into the centerof the Fan 7 and the Fan Centering Disk 8, FIG, 6 & 7. The Fan 7 is seton the Base Ring 9 and rotated clockwise until the edges of the Fan 7slide under the Fan Guides 5; and come into contact with the Fan Stops6, and the Locking Washers 14 rest in the Locking Indents 5 b, as shownin FIG. 13. The Twist Top Hole Saw is now ready to cut.

How The Invention Works: The Invention works by setting the Fan Unit,FIGS. 6 & 7, with the attached Mandrel Unit, FIGS. 3, 4 & 5, firmly ontop of the Base Ring 9 of the Saw Unit, FIGS. 1 & 2. The Fan Unit, FIGS.6 & 7, is then rotated clockwise, approximately ninety degrees, asindicated by FIGS. 12 & 13, bringing the Fan 7 into place between theBase Ring 9 and the Fan Guides 5 and in contact with the Fan Stops 6.The fan 7 is held in position by the Locking Washers 14 pressing intothe Locking Indents 5 b. The Fan Stops 6 are slightly thicker than theFan 7 so as to allow sufficient Clearance 13 for the Fan 7 to slidebetween the Base Ring 9 and the Fan Guides 5. We now have an operationalHole Saw that will cut a circular hole through whatever material we havechosen to penetrate.

How to use the invention: The assembled Hole Saw, FIGS. 10 & 11, isattached to a drill by inserting the Hex Shank 2 or the Bit Shank 1 intoa drill chuck. The Pilot Bit 11 is pressed against the material throughwhich the saw will penetrate. The drill is activated causing the PilotBit 11 to guide the Saw Blade 12 onto and through the selected material.This results in a hole being cut through the material, and the cutportion (core) of the material most likely to remain jammed within thecavity of the Saw Blade 12.

The Hole Saw, with the jammed core, is removed from the hole. The chuckof the drill is firmly grasped with one hand and the Saw Blade 12 withthe other. The Saw Unit, FIG. 1&2, is twisted clockwise and the chuck,holding the Mandrel Unit, FIG. 3, 4 &5, counterclockwise. Thisdisengages the Locking Washer 14 from the Locking Indent 5 b and allowsthe Fan 7 to rotate free of the Fan Stops 6 and the Fan Guides 5. Thetapered Pilot Bit 11 has created a slight cone shaped hole in the core.This allows for easy extraction of the Pilot Bit 11 from the core; asthe Fan Unit, FIGS. 6 & 7, and Mandrel Unit FIGS. 3, 4 & 5, is liftedfrom the Base Ring 9. A large portion of the core top is now exposed andcan be easily pressed from the interior of the Saw Blade 12; if it hasnot already fallen free due to the removal of the Pilot Bit 11. In theevent the drill is powered in reverse to separate the Fan Unit, FIGS. 6& 7, from the Saw Unit, FIG. 1&2, the beveled edges (6 a and 5 a) of theFan Stops 6 and Fan Guides 5 will cause the Fan 7 to ride up and overthe Fan Guides 5, again separating the Fan Unit, FIGS. 6 & 7, from theSaw Unit, FIG. 1&2

All elements are necessary. Further testing may indicate improvements indesign and/or materials.

This design is meant to apply to all sizes of Hole Saws. With thepossible exception of the Mandrel, FIGS. 3, 4 & 5, measurements will besomewhat proportionally adjusted as the diameter of the Saw Bladechanges.

What I claim as my invention is a separating hole saw with a convenientlocking and unlocking device, and tapered drill bit that allows for thequick removal of the top of the saw from the lower (blade) portion ofthe saw; thereby providing for the easy removal of the sawed materialfrom within the confines of the circular saw blade:
 1. Replacing thestandard flat surface on the top of the saw, is a metal ring with alarge opening. This ring is attached to the interior circumference ofthe upper part of the saw blade.
 2. The locking device consists of ametal plate with diametrically opposed increasing radii along 180degrees swing on each side. This plate rests on the surface of theaforementioned ring and rotates into place between a set of arched metalstrips placed on that ring. For the purpose of this claim the strips aredesigned so that the lower portion (plate contacting surface) isslightly indented. This creates an overhang that will hold the plate,when in the locked position, against the ring. The strips are located ontop of and on opposite sides of the ring. The strips are arched and setin such a manner that their total plate connecting surfaces will press,with equal force, against the two diametrically opposed sections of theplate's edge, as that plate is rotated into the locked position. Due tothe off center design of the plate and strips, the plate is held inplace by torque, and the overhang feature of the strips, while the sawis cutting. At other times, the plate is prevented from rotating out ofposition by friction provided by rubber washers attached to the top ofthe plate that press against the upper (overhanging) part of the strips.The limited projection of the overhang is such that it will allow theplate to clear its confines when rotated to the unlocked position. Thelocking torque translates into the driving force for the hole saw toperform its cutting action.
 3. A tapered drill bit (pilot bit) isincorporated into the design so as to create a slight cone within thesawed material. This facilitates ease of retraction of the bit as theplate is rotated free of the confines of the contacts and lifted fromthe aforementioned ring.